Thermal analysis of neuroleptic drugs and vitamins

The thermal decomposition of 41 drugs containing acetylsalicylic acid, 5-pyrazolone derivatives, the components stimulating the central nervous system, the Aviomarin, Glutamic acid, and Laxative chocolate tablets, and vitamins has been studied by employing the differential thermal analysis (DTA), thermogravimetry (TG), and differential TG (DTG) techniques. The possibility has been demonstrated to employ the DTA, TG, and DTG curves of their thermal decomposition for the identification of particular dosage forms and for the qualitative and quantitative monitoring of their composition. Based on the stages due to dehydration, decarboxylation, and formation of intermediate decomposition products, the content of the active components was determined in 17 of the drugs. The results of the determinations were in good agreement with those calculated from information supplied by the manufacturers.     

DSC characterisation of compression moulded PEEK-PTFE plaques

Thermal behaviour of substituted monoazo dyes I-XVI, have been investigated by means of differential thermal analysis (DTA) and thermogravimetry (TG). The thermal stabilities of these dyes have been determined using the DTA and TG curves and the influence of the substituents and intramolecular hydrogen bonds on the DTA and TG curves of the dyes together with the melting points were also examined. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal stability of anti-rheumatic pharmaceutical drugs parecoxib sodium and valdecoxib

Thermal analysis of antirheumatic drugs, parecoxib sodium (PCX) and valdecoxib (VCX) was achieved. Thermogravimetry (TG), derivative thermogravimetry (DTG), and differential thermal analysis (DTA) were used through the work. The results led to thermal stability data, and also to the determination of kinetic parameters such as activation energy and frequency factor. The differential scanning calorimetry (DSC) was suitable for the purity determination of the compounds. The simplicity, speed, and low operational costs of thermal analysis justify its application in the quality control of pharmaceutical drugs.     

Application of thermal analysis to the study of antituberculosis drugs–excipient compatibility

First-line drugs (rifampicin, RIF; isoniazid, INH; ethambutol, ETA; and pyrazinamide, PZA) recommended in conventional treatment of tuberculosis were analyzed in 1:1 w/w binary mixtures with microcrystalline cellulose MC 101 (CEL) and lactose supertab^® (LAC) by differential scanning calorimetry (DSC), thermogravimetry (TG), differential thermal analysis (DTA), and Fourier transformed infrared analysis (FTIR) as part of development of fixed dose combination (FDC) tablets. Evidence of interaction between drug and pharmaceutical excipients was supposed when peaks disappearance or shifting were observed on DTA and DSC curves, as well as decreasing of decomposition temperature onset and TG profiles, comparing to pure species data submitted to the same conditions. LAC was showed to interact with RIF (absence of drug fusion and recrystallization events on DSC/DTA curves); INH (thermal events of the mixtures different from those observed for drug and excipient pure in DSC/DTA curves); PZA (decrease on drug fusion peak in DSC/DTA curves), and ETA (shift on drug onset fusion and absence of pure LAC events on DSC/DTA curves). In all cases, an important decrease on the temperature of drug decomposition was verified for the mixtures (TG analysis). However, FTIR analysis showed good correlation between theoretical and experimental drug-LAC spectra except for INH–LAC mixture, evidencing high incompatibility between these two species and suggesting that those interactions with PZA and RIF were thermally induced. No evidence of incompatibilities in CEL mixtures was observed to any of the four-studied drugs.     

Thermal characterisation of Australian oil shales

There has been a significant research effort on the development of an oil industry based on Australian oil shales. However, to date the research has been based mainly on the processing aspects of oil shale. The thermal analyses of oil shales, while having been the subject of many studies, have been limited to some extent by instrumentation and analytical techniques. This paper reports on thermal analysis studies utilising traditional thermogravimetry/differential thermal analysis (TG/DTA) and differential scanning calorimetry (DSC). The application of modern thermal analysis techniques such as high resolution TG (HRTG) and modulated differential scanning calorimetry (MDSC) is also examined and compared to the traditional methods.     

Thermal Behaviour of Raw Fly Ashes

Thermal behaviour of raw fly ashes-wasted products from various Polish power plants has been investigated using X-ray diffractions (XRD), Fourier transform infrared spectroscopic (FT-IR), differential thermal analysis (DTA) and thermogravimetry (TG). On the basis of the DTA and TG analysis differentiation between examined ashes has been made, which could not be achieved by XRD and FT-IR methods. This revised version was published online in July 2006 with corrections to the Cover Date.     

Preparation, crystal structure, and thermolysis of phenylenediammonium diperchlorate salts

Three salts of phenylenediammonium diperchlorate have been prepared and characterized by X-ray crystallography. Their thermal decomposition has been studied by thermogravimetry (TG), differential thermal analysis (DTA), and explosion delay (DE) measurements. The kinetics of thermal decomposition was evaluated by model fitting and isoconversional methods using TG data. The oxidation-reduction reactions near the surface of thermolysing perchlorates may be responsible for the decomposition followed by explosion. The possible pathways of thermolysis have also been proposed.     

Thermal analysis of N-phenylbenzohydroxamic acid (PBHA)

The thermal dissociation of N-phenylbenzohydroxamic acid was studied by differential thermal analysis (DTA) and thermogravimetry (TG). The DTA curve showed two exothermic peaks caused by melting and/or decomposition of the compound.     

Thermal characteristics of novel NaH2PO4/NaHSO4 flame retardant system for polyurethane foams

The thermal decomposition of iminodiacetic, oxydiacetic, and thiodiacetic acids in helium atmosphere has been studied by means of thermogravimetry (TG), differential thermal analysis (DTA) and temperature-programmed pyrolysis directly coupled with mass spectrometry (TPPy-MS). Evolved gas analysis (EGA) profiles of iminodiacetic and oxydiacetic acids were obtained and compared with TG and DTA profiles. The decomposition of iminodiacetic acid forms water, CO, CO₂, CH₃CN, HCN and some hydrocarbons. After water evolution a cyclic anhydride is formed, as well as for oxydiacetic acid. Thiodiacetic acid vaporizes without decomposition.     

Synthesis,characterization and thermal behavior on solid tartrates of light trivalent lanthanides

Solid state Ln–L compounds, where Ln stands for light trivalent lanthanides (L–Gd) and L is tartrate, have been synthesized. Thermogravimetry and differential thermal analysis (TG/DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results led to information about the composition, dehydration and thermal decomposition of the isolated compounds.     

Study on thermal decomposition of polymers by simultaneous measurement of TG–DTA and miniature ion trap mass spectrometry equipped with skimmer-type interface

Simultaneous thermogravimetry–differential thermal analysis and miniature ion trap mass spectrometry (TG–DTA–ITMS) instrument equipped with a skimmer-type interface has been successfully developed. The system allows precise real-time monitoring analysis of activated organic compounds such as pyrolysates because gaseous transformation of the evolved gases from the TG–DTA is suppressed by the skimmer-type interface. Also, excessive fragmentation during ionization of molecules can be avoided with the soft ionization method by photoionization. In addition, the miniaturized ITMS is equipped with unique tandem MS capability. These features permit a better understanding of the complicated thermal behavior and the precise pyrolysates of materials. The pyrolysis of various standard reagent polymers such as polymethyl methacrylate, polystyrene, and polyphenylene sulfide has been examined by the TG–DTA–ITMS in inert atmosphere. The synergy effect of the skimmer-type interface and the ITMS was evaluated comparatively with conventional quadrupole mass spectrometry results. It was confirmed that the real-time monitoring ITMS/MS worked satisfactorily. Here, we demonstrate a valuable application of the TG–DTA–ITMS in the detailed analysis of commercial polymers.     

Formation of B-C-N Ceramics Investigated by Emanation Thermal Analysis, TG and DTA

Processes taking place during formation of B-C-N ceramics by thermal treatment of organic precursors were investigated using emanation thermal analysis (ETA), differential thermal analysis (DTA) and thermogravimetry (TG). An additional information about thermal behavior of precursors used for preparation of BC4N, BN and CNx ceramic systems by heating in argon up to 1100°C was obtained. The ETA enabled us to characterize microstructure changes in the samples at in situ conditions of thermal treatment. A good agreement of ETA, TG and DTA results was found. This revised version was published online in August 2006 with corrections to the Cover Date.     

Selected thermoanalytical methods and their applications from medicine to construction

There are many thermoanalytical techniques but only several of them such as thermogravimetric analysis (TG), high resolution thermogravimetric analysis (Hi-Res™ TG), derivative thermogravimetry (DTG), differential thermal analysis (DTA), calorimetry, differential scanning calorimetry (DSC), modulated differential scanning calorimetry (MDSC), evolved gas analysis (EGA), transient thermal analysis (TTA) and thermal conductivity (k) have selected to be discussed in this paper. Simultaneous thermal analysis (STA) is ideal for investigating issues such as the glass transition of modified glasses, binder burnout, dehydration of ceramic materials or decomposition behaviour of inorganic building materials, also with gas analysis. Selected applications of various thermoanalytical techniques from medicine to construction have also been discussed in this paper.     

THERMAL DECOMPOSITION OF METAL COMPLEXES. MIXED COMPLEXES OF DIVALENT TRANSITION METALS WITH α-NITROKETONES

Abstract

The thermal behaviour of mixed complexes containing transition metals, α-nitroketones and pyridine or ethanol was investigated by thermogravimetric analysis (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). The values of the activation energies and the enthalpies for the dissociation processes have been calculated in high vacuum and isothermal conditions. Comments are made on the obtained heats and correlations with structural characteristics are looked for.     

Thermal analysis of a model bio-membrane

Thermal properties of some shedded snake skins in comparison with human skins are represented by thermogravimetry (TG), derivative thermogravimetry (DTG), and differential thermal analysis (DTA) to predict process condition as dermal pathway for administration of drugs or it be used as model membranes for permeation studies. Thermal behavior by TG/DTG and DTA curves for four kinds of shedded snake skins as Boelens Python (BP), Eastern Indigo Snake (EIS), Emerald Tree Boa (ETB), and Cascavel (CBR) were similar in relation to their decomposition temperatures at 100 °C and 230–400 °C of its constituents, however, their properties were different in the residue content (inorganic or carbonaceous substances). Similar thermal properties were also exhibited by human skins’ samples, however, they presented different residue and constituents’ content.     

Thermal behavior of drugs

Data on the thermal stability of drugs was required to obtain information for handling, storage, shelf life and usage. In this study, the thermal stability of two nonsteroidal anti-inflammatory drugs (NSAIDs) was determined by differential scanning calorimetry (DSC) and simultaneous thermogravimetery/differential thermal analysis (TG/DTA) techniques. The results of TG analysis revealed that the main thermal degradation for the naproxen and celecoxib occurs in the temperature ranges of 196–300 and 245–359 °C, respectively. The TG/DTA analysis of compounds indicates that naproxen melts (at about 158.1 °C) before it decomposes. However, the thermal decomposition of the celecoxib started about 185 °C after its melting. The influence of the heating rate (5, 10, 15, and 20 °C min⁻¹) on the DSC behavior of the both drug samples was verified. The results showed that, as the heating rate was increased, decomposition temperatures of the compounds were increased. Also, the kinetic parameters such as activation energy and frequency factor for the compounds were obtained from the DSC data by non-isothermal methods proposed by ASTM E696 and Ozawa. Based on the values of activation energy obtained by various methods, the following order for the thermal stability was noticed: naproxen > celecoxib. Finally, the values of ΔS ^#, ΔH ^#, and ΔG ^# of their decomposition reaction were calculated.     

UO<Subscript>2</Subscript>(VI), Sn(IV), Th(IV) and Li(I) complexes of 4-azomalononitrile antipyrine

UO₂(VI), Sn(IV), Th(IV) and Li(I) complexes of 4-azomalononitrile antipyrine (L) have been isolated and characterized based on IR spectra, ¹H NMR, elemental analyses, molar conductance and thermal analysis (DTA/TG). The study revealed that the ligand behaves as a neutral bidentate one and coordination takes place via the carbonyl atom of pyrazolone ring >C=O and the azomethine nitrogen >C=N. The thermal stability of the metal complexes were investigated by thermogravimetry (TG), differential thermal analysis (DTA) techniques and infrared spectra, and correlated to their structure. The thermal study revealed that Th(IV) complexes show lower thermal stability than both UO₂(VI) and Sn(IV) complexes.     

Etude sur le comportement thermique de quelques polymeres ignifugeants contenant du phosphore et des halogenes

The thermal behaviour a series of polyphosphonates was studied by thermogravimetry (TG) and differential thermal analysis (DTA). The obtained data permitted the calculation of activation energies and reaction orders on decomposition zones by the Coats — Redfern method.     

Thermoanalytical methods in pharmaceutical technology

A short survey is given of some aspects of the application of thermoanalytical methods, especially differential thermal analysis (DTA), differential scanning calorimetry (DSC) and thermogravimetry (TG), in solid-dosage technology. The usefulness of these methods in the prediction of drug-excipient compatibility, studies of solid-dispersion systems, the analysis of enantiomers and racemates, measurement of the time of tablet disintegration, the analysis of drug formulations and studies of the processes of grinding and drying of drugs is discussed.

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Zusammenfassung Es wird ein kurzer Überblick über einige Aspekte der Anwendung von thermoanalytischen Methoden, insbesondere von DTA, DSC und TG in der Feststoffdosierung gegeben. Weiterhin wird die Nützlichkeit dieser Methoden bei der Voraussage der Bindemittelverträglichkeit, bei der Untersuchung disperser Feststoffsysteme, bei der Analyse von Enantiomeren und Racematen, bei der Messung der Tablettenzerfallszeit, bei der Analyse der Arzneimittelformierung und bei der Untersuchung von Mahl- und Trocknungsprozessen bei Arzneimitteln diskutiert.

     

The thermal decomposition of aqueous manganese (II) nitrate solution

The thermal decomposition of commercially available aqueous solutions of manganese(II) nitrate was investigated using the conventional thermal analytical techniques of thermogravimetry (TG), differential thermal analysis (DTA), and evolved gas analysis (EGA). Infrared spectra and X-ray diffraction patterns were used to help characterize intermediate species.